A. Field of the Invention
The present invention relates to an ultrasonic treatment apparatus for medical treatments, which is adapted to break up a ureteral stone or excise a thrombus by use of ultrasonic vibrations.
B. Description of the Prior Art
A typical ultrasonic treatment apparatus which breaks up a stone formed in a living body-especially in the ureter, the pelvis, a bile duct, or the like-by use of ultrasonic vibrations, is disclosed in, for example, Japanese Utility Model Disclosure (KOKAI) No. 60-55408 and U.S. Pat. No. 3,830,240. In this ultrasonic treatment apparatus, the vibration transmission member for transmitting ultrasonic vibrations has elasticity. In an ultrasonic treatment apparatus having another arrangement, disclosed in Japanese Utility Model Disclosure (KOKAI) No. 60-55409, the vibration transmission member is enclosed within a sheath, and a perfusate is able to flow through a space therebetween.
In the typical ultrasonic treatment apparatus, a longitudinal passage formed at the center of an oscillator is communicated with the through-hole of a pipe-like vibration transmission member, and cooling water flows through the passage to remove the heat generated by the vibrating of the oscillator.
However, if the vibration transmission member is made thinner to improve its elasticity, the cross-sectional area of the through-hole of the transmission member will be reduced, and hence satisfactory cooling cannot be provided, due to a consequent reduction in the flow rate of the perfusate.
In the ultrasonic treatment apparatus having the vibration transmission member enclosed within the sheath, if the cross-sectional area of the passage constituted by the space between the sheath and the transmission member is sufficiently maintained, the outer diameter of the overall insertion portion is enlarged, and hence the elasticity of the vibration transmission member is degraded.
A pipe made of a metal having elasticity is used as the vibration transmission member of the ultrasonic treatment apparatus disclosed in the Japanese Utility Model Disclosure (KOKAI) No. 60-55408. The vibration transmission member is inserted into a body cavity via a channel of an endoscope so as to be used for a medical treatment.
More specifically, the transmission member of the ultrasonic treatment apparatus is inserted into the channel through a forceps opening of the endoscope, and the distal end of the transmission member is made to protrude, from the distal end of the endoscope insertion portion, a length suitable for a treatment, this being normally 5 mm to 10 mm. Thereafter, the protruding vibration transmission member is pressed against a stone so as to break up the stone by means of the ultrasonic vibrations produced thereby.
In general, a forceps opening of the endoscope is obliquely formed with respect to the axis of the insertion portion, and a channel communicating with the forceps opening is bent inside an endoscope operation portion. For this reason, if the transmission member is inserted, from the forceps opening, into the channel, it comes into contact with the inner wall at a bent portion of the channel and hence is subjected to a straightening force.
The transmission member of the ultrasonic treatment apparatus alternately corresponds to loops and nodes of ultrasonic vibrations. For this reason, upon insertion of the transmission member into the endoscope channel, if the member portion corresponding to a loop of the vibration is brought into contact with the inner wall, the ultrasonic vibration is attenuated at this position, thereby disabling an effective treatment.
In order to eliminate the above problem, there is proposed an endoscope which is provided with a channel having no bent portion so that a forceps opening is formed substantially on an extention line of the axis of the insertion portion. In this endoscope, however, an eyepiece is deviated from the extension line of the axis. When the endoscope insertion portion is to be inserted into the body cavity, the operator must insert it while observing from the eyepiece. Therefore, if the eyepiece is deviated from the extension line of the axis of the insertion portion, operability is considerably degraded.